Why should you care about loading 3d models into a web browser? Think about this scenario:
A property management company has invested the time and money to get all their buildings into a BIM and now want to manipulate that at each respective location for FM. We all know how big these files get and the hardware required to handle the data is expensive. What about the property owner running (or outsourcing) their own data center to house all the models with sufficient hardware to navigate and manipulate said models and then letting the FM person for each location access the BIM through a web browser at their site?
Or, you want to enable a client to review certain aspects of a project but they don't have the software/hardware to access the project you've developed in BIM? Simply have them navigate to a web page where they can see what you need them to.
Granted the technology is in it's infancy, but I for one would tend to agree with Tom's statement at Inside the Factory that this is a turning point for 3d on the web.
In an echo of a recent post from Inside the Factory, you should check out 3d in your web browser if you haven't yet. It will WOW you...
P.S. - you need firefox 4.x to see this easily, otherwise Tom lists other options for doing so. Now, If I can just help my co-worker print from Excel, we can say the future is here!